Torch Cuts out.

[grindergary]

OK, so I got smart and decided to upgrade my system with CandCNC's feather touch set up for ohmic sensing.
I cut a couple sheets of 1/2" plate and the difference was better. With or without THC.

I set up to show off some sign cutting with 16 gauge plate. The torch touched of, proceeded to cut and as soon as it was into the cut the torch would stop. No errors on plasma machine. New nozzle and electrode. Restart and it would do it again.

The stops were random as they could be on tight cutouts and on long curved lines.

I sent an email to Jim Colt and he didn't have an answer as to the problem. He asked more questions so he will likely chime in here.

I cut another half sheet of 1/2" this morning and it cut great.

I really don't want to remove the ohmic sensor but may have too. Can't make any money if the machine can't cut light material.

Tom at Candcnc says it might be a setting but i checked everything over and over and looks like the manual states.

Anyone have any ideas?

Thanks

Gary

[plasmapros]

What nozzle, amperage, and cut speed are you using on this 16g? My initial guess without any info is that you may be travelling too slow. Have you followed the amperage and speed guidelines in your plasma operators manual?

[grindergary]

What nozzle, amperage, and cut speed are you using on this 16g? My initial guess without any info is that you may be travelling too slow. Have you followed the amperage and speed guidelines in your plasma operators manual?

PLasmapros,
Yup been using the cut charts from HT. same settings as before the change to ohmic sensor.

It does cut well, just can't keep having it stop mid cut.

Thanks for your reply

Gary

[beefy]

What nozzle, amperage, and cut speed are you using on this 16g? My initial guess without any info is that you may be travelling too slow. Have you followed the amperage and speed guidelines in your plasma operators manual?

This is something along the lines of what I'm thinking too. I'm wondering if you are actually getting a lost arc condition because the thin sheet is vaporising too fast and leaving no metal to maintain the arc. Do some test cuts on scrap and try speeding up the cut or reducing the amps.

Good luck.

Keith.

[grindergary]

What nozzle, amperage, and cut speed are you using on this 16g? My initial guess without any info is that you may be travelling too slow. Have you followed the amperage and speed guidelines in your plasma operators manual?

This is something along the lines of what I'm thinking too. I'm wondering if you are actually getting a lost arc condition because the thin sheet is vaporising too fast and leaving no metal to maintain the arc. Do some test cuts on scrap and try speeding up the cut or reducing the amps.

Good luck.

Keith.

Keith,

I did some test cuts and at 78 volts 45 amps, I am holding .06 cut height. Tried different speeds and almost same except for the cuts look like the cuts are thinner. The cuts are clean and dross free. I then tried 40 amp and different speeds. Not much difference.

I cut some long straight cuts and then some outside profiles. No problem.

I then tried to cut a cross I found on the site with alot of inside detail. I tried to cut 16 ga with the above settings and got 90% of the way thru the file and it stopped again.It was not on a tight cut. was a longer curved cut.

So, I loaded up a sheet of 10 ga. for a small job and cut the same cross out with book specs and not a problem. Frustrating

It is not the ohmic set up and I am without it .Just using touch off with old set up.

I know I can cut this because I have cut many pieces of 16 ga. without a problem with the same set up.

Anyone have any ideas?

[muzza]

Your torch volts in not going outside your upper or lower fault limit is it?
Murray

[beefy]

Guess the first thing is to eliminate what is turning the torch off. Is it the controller or is it the plasma cutter itself. Make sure "torch off on arc loss" is not ticked in cut profiles. Keep an eye on the "torch on" LED on the high voltage card. If the torch turns off while you still have the torch on signal then it's the plasma cutter itself which is turning off the torch.

If it is the plasma torch that is turning off the torch then perhaps you could keep a close eye on the amps while cutting, because the plasma unit itself will turn the torch off if it senses arc loss. Do the amps vary, and especially do they go down just before the arc extinguishes. If you always have the torch on signal (LED on high voltage card), the volts is kept pretty steady, and the amps stay steady, yet the torch switches off, then it seems like a plasma unit issue.

If it's the torch on signal from the computer turning off then you know the plasma unit is being commanded to turn off and troubleshooting starts on the computer end.

That should at least narrow down the troubleshooting for now.

You might need another hand to watch some of the above parameters while you are watching another one.

Keith.

[grindergary]

Beefy,
Thanks for the guidelines.
I have followed your suggestions as best as I could. Amps steady and voltage goes ok till just before it cuts out.

I think the problem is that the voltage rises as the torch is moving on the tight curves. Almost like trying to cut a small hole with the THC on and the speed becomes too fast for the torch to keep up or as with a hole the edge tapers. Not noticeable on 16 gauge.

So, knowing that that may be what is happening, I am thinking that I may have to slow down on inside profiles on this stuff.

Funny though, it cut ok before on the same files as before.

Any ideas as to what might help?

Gary

[beefy]

Just from what you are saying it appears the cut parameters are good i.e. amps constant and voltage constant. If they are holding good then the plasma cutter itself should not be turning itself off.

You haven't mentioned anything about my suggested check of the "torch on" LED on the high voltage card. Does it remain on when the torch goes off or does it go off at the same time as the torch turns off. This is to try and figure out if the PC/Mach is telling the plasma cutter to switch off or is it the plasma cutter itself deciding it will switch off.

I'm a bit confused by something contradictory you said. You say you think the problem is that the voltage rises as the torch is moving on the tight curves. However, you also say the amps are volts are steady before the torch cuts out. Are you saying that at some point in the cut (tight curves) the voltage climbed but then came back to normal and the torch cut out while the volts and amps were at their steady values.

Keith.

[grindergary]

Hi Beefy,
I noticed that the voltage would spike on a tight curve but so fast it was hard to catch. When running a long curve say 4 inch diameter, amps and volts are good. I am thinking the torch runs out of material and the torch tries to move but not fast enough on those tight spots. Just my thoughts.

The torch led stays on when torch stops. Movement continues with both x and y axis. Seems to stop on next line. I'm new at most of the g code part.

The thing I think is that when the torch follows a tight curve, the torch loses arc because it is moving too slow? I'm not sure but seems that way.

Cut some stuff today finally and worked good on all outside profiles. Inside on one torch stopped. I am also wondering if I should be able to have the movement go faster on tight curves. Not sure how to do that.

Its getting busy again so back to cutting 1/2" material again.

Thanks for your time with this. I know I will get it going soon.

Gary

[grindergary]

OK I cut this sign I got from the downloads area. You can see the bottom right side the one part did not cut out and the H in either did not cut. The machine did not stop and the torch light stayed on the monitor and the the card. I'm at a loss as to what to do now. The torch just stopped till the next line with a touch off and fired again and kept going till it decided to stop again.

I cut an oval from Jason and it was a lot more detailed cutting with smaller cut outs and it cut really well back in February of this year.

Talked to HT support and they went thru the plasma with tests like air pressure and all connections. They say if it was the plasma it would more than likely show a fault code. No fault code.

I am about ready to try another computer and see if that helps.

Gary

[beefy]

Gary,

first of all just regarding your acceleration settings (Config / Motor Tuning), my Candcnc manual says to set between 25 and 50 ipss. However I can't see this being the issue seeing as the torch also cuts out on long stretches of cut.

The sign you posted seems to show a completely new problem. From what I can see the cut didn't even start in those two areas. Doing a dry run of that file (Plasma cutter off, THC off, Auto THC On in cut profiles off) should show you if the torch on LED comes on at the start / pierce point for those two locations. If not maybe that's the gcode.

You know what I'd do in this situation, I'd make a zig zaggy cut file which goes for a long time. Just one pierce then a lot of cutting going all over the place with sharp turns, etc. Chuck some long lines in there too seeing as the torch has cut out under these conditions too.

First of all make sure the wiring for your torch on signal is good, i.e. from the high voltage card to the plasma cutter. This is just to rule out a loose/broken wire/bad connection in this area. Wire a switch in parallel with the torch on wires (from the Hypertherm) where they connect to the high voltage card terminal block. As soon as cutting starts flick the switch. You now have a hardwired torch on system. Have the wires to this switch long enough so you are holding the switch while watching your PC screen. Watch the volts and amps carefully.

If the cut makes it all the way then you have to remember to turn the switch off just before the cut ends or yourtorch will stay on.

If the torch cuts out while volts and amps are steady then it's the Hypertherm switching off for some reason. Changing your computer will not stop that.

Lets think what the Hypertherm needs to operate:
* Its power source
* Air supply
* Torch on input (which it gets from the PC)
* Of course you also need a good ground but I'm thinking monitoring the volts and amps is an indication that all is good in that area.

The "torch on" input is the only thing it gets from the PC. You will be giving this to it with your bypass switch to rule out the PC momentarilly dropping this out.

If this test show the Hypertherm to still be dropping out while volts and amps show steady then ask Hypertherm what they think. They can't tell you it's you PC shutting it down at least. The Hypertherm is shutting itself down for some reason.

Keith.

[grindergary]

Ya bad picture. only have my cell phone with me. The areas did pierce and start to cut but lost arc. The bottom one started, moves about 3/8 of an inch and stopped.

I will try your suggestion but for now I have a ton of plate to cut. All 1/2 and 3/8 inch stuff. All squares and rectangles. No problem cutting that. Have to get some cash flow again or i'm toast LOL.

I will let you know as soon as I can try your ideas.

Thanks

Gary

[beefy]

Ha ha, happy for you Gary.

That's a problem I need, working towards it (i.e. cutting jobs).

Keith.

[skiwithnoskis]

My plasma cam and HT 1250 does this too sporadically. I still haven't figured it out.

Good luck

[vmax549]

One more suggested test. Take the leads for the torch on relay and power up a small light bulb Use Keiths idea for a bypass switch to fire the torch . THEN run a program and see IF the light bulbs stays on while the torch is suppose to be on.

This will tell IF the problem is in the electronics (relay drops out) or the torch (drops out while in bypass,it should not).

I have seen Mach3 problems(failes to run M3 macro), Electronics (CandCNC relays droping out) and Torch problems cause what you see. The trick is to isolate each unit to find the root cause, Hint sometimes it is 2 problems from seperate functions.

Just a thought, (;-) TP

[grindergary]

Terry,

Thanks for the reply.
I tried everything you suggested as well as Keith,s ideas.

Everything seems to be working now. I can't get it to stop again. Ghosts? I don;t know.
Anyways, as the saying goes if it ain't broke leave it alone.
I want to keep cutting my art stuff but work keeps getting in the way. Nice.

Thanks guys,

Gary